Maneuvers is best for Defenders, but is pretty sucky anyhow if I remember the numbers from the CoH character builder correctly. I would go with Replusion Field or Force Bubble instead at 32; either one can be very useful for pushing back enemies and helping out allies in over their head.
I'd go with Force Bubble, mainly for the reason it's more impressive a power and better in PvP, but also because of the larger range. For this reason though it must be used carefully due the the mass aggro you can attract to yourself and the positions you can end up putting your enemies in.
The mass aggro can be a good thing at times though as it can work as a makeshift taunt and get enemies to hit (and miss) you as you hide in your Personal Force Field (hopefully with Dispersion Bubble up too) and give a Tanker that much needed breather.
The Smoking Demon
Ash/Tar Corruptor
Union
@The Smoking Demon
As a bubbler, get maneuvers before Assault, it stacks with your bubbles to give 44 defence rather than 39. That means people take almost half the damage.
@Unthing ... Mostly on Union.
I'd slot Irradiate with debuff Def, it's the most powerful in the rad secondary, so is worth slotting for it.
Defiant 50's
Many and varied!
@Miss Chief
New build 
---------------------------------------------
01) --> Personal Force Field==> DefBuf(1) DefBuf(15) DefBuf(23)
01) --> Neutrino Bolt==> Acc(1) EndRdx(3) Dmg(3) Dmg(33) Dmg(34) DefDeBuf(46)
02) --> X-Ray Beam==> Acc(2) EndRdx(5) Dmg(5) Dmg(34) Dmg(34) DefDeBuf(40)
04) --> Deflection Shield==> DefBuf(4) DefBuf(7) DefBuf(7)
06) --> Hurdle==> Jump(6) Jump(21) Jump(37)
08) --> Insulation Shield==> DefBuf(8) DefBuf(9) DefBuf(9)
10) --> Hasten==> Rechg(10) Rechg(11) Rechg(11)
12) --> Dispersion Bubble==> EndRdx(12) DefBuf(13) DefBuf(13) DefBuf(15)
14) --> Super Speed==> Run(14)
16) --> Health==> Heal(16) Heal(17) Heal(17)
18) --> Maneuvers==> EndRdx(18) DefBuf(19) DefBuf(19) DefBuf(27)
20) --> Stamina==> EndMod(20) EndMod(21) EndMod(23)
22) --> Assault==> EndRdx(22)
24) --> Tactics==> EndRdx(24) TH_Buf(25) TH_Buf(25) TH_Buf(27)
26) --> Repulsion Bomb==> Acc(26) EndRdx(29) DisDur(43) DisDur(43) DisDur(43)
28) --> Cosmic Burst==> Acc(28) EndRdx(29) Dmg(31) Dmg(31) Dmg(31) DefDeBuf(50)
30) --> Combat Jumping==> Jump(30) Jump(37) Jump(42)
32) --> Force Bubble==> EndRdx(32) EndRdx(33) EndRdx(33)
35) --> Neutron Bomb==> Acc(35) EndRdx(36) Dmg(36) Dmg(36) Dmg(37) DefDeBuf(50)
38) --> Atomic Blast==> Dmg(38) Dmg(39) Dmg(39) Rechg(39) Rechg(40) Rechg(40)
41) --> Conserve Power==> Rechg(41) Rechg(42) Rechg(42)
44) --> Power Build Up==> Rechg(44) Rechg(45) Rechg(45) TH_Buf(45) TH_Buf(46) TH_Buf(46)
47) --> Proton Volley==> Acc(47) EndRdx(48) Dmg(48) Dmg(48) Dmg(50)
49) --> Swift==> Run(49)
---------------------------------------------
01) --> Sprint==> Jump(1)
01) --> Brawl==> Acc(1)
01) --> Vigilance==> Empty(1)
02) --> Rest==> Rechg(2)
---------------------------------------------
Hmmm i can't see Force Bolt here, IMO for a bubbler it is my real panic button instead of PFF. You can beat any color up to red one on one by using Force Bolt. Quick recharge and good Knockback. Also you can use it to protect blasters or other defenders if they don't have any KB power, trollers usually have good holds for stoping them.
How about this?
---------------------------------------------
01) --> Personal Force Field==> DefBuf(1) DefBuf(15) DefBuf(23)
01) --> Neutrino Bolt==> Acc(1) EndRdx(3) Dmg(3) Dmg(33) Dmg(34) DefDeBuf(46)
02) --> X-Ray Beam==> Acc(2) EndRdx(5) Dmg(5) Dmg(34) Dmg(34) DefDeBuf(40)
04) --> Deflection Shield==> DefBuf(4) DefBuf(7) DefBuf(7)
06) --> Hurdle==> Jump(6) Jump(21) Jump(37)
08) --> Insulation Shield==> DefBuf(8) DefBuf(9) DefBuf(9)
10) --> Hasten==> Rechg(10) Rechg(11) Rechg(11)
12) --> Dispersion Bubble==> EndRdx(12) DefBuf(13) DefBuf(13) DefBuf(15)
14) --> Super Speed==> Run(14)
16) --> Health==> Heal(16) Heal(17) Heal(17)
18) --> Maneuvers==> EndRdx(18) DefBuf(19) DefBuf(19) DefBuf(27)
20) --> Stamina==> EndMod(20) EndMod(21) EndMod(23)
22) --> Assault==> EndRdx(22)
24) --> Tactics==> EndRdx(24) TH_Buf(25) TH_Buf(25) TH_Buf(27)
26) --> Repulsion Bomb==> Acc(26) EndRdx(29) DisDur(43) DisDur(43) DisDur(43)
28) --> Cosmic Burst==> Acc(28) EndRdx(29) Dmg(31) Dmg(37) Dmg(42) DefDeBuf(50)
30) --> Force Bolt==> Acc(30) EndRdx(31) KB_Dist(31)
32) --> Force Bubble==> EndRdx(32) EndRdx(33) EndRdx(33)
35) --> Neutron Bomb==> Acc(35) EndRdx(36) Dmg(36) Dmg(36) Dmg(37) DefDeBuf(50)
38) --> Atomic Blast==> Dmg(38) Dmg(39) Dmg(39) Rechg(39) Rechg(40) Rechg(40)
41) --> Conserve Power==> Rechg(41) Rechg(42) Rechg(42)
44) --> Power Build Up==> Rechg(44) Rechg(45) Rechg(45) TH_Buf(45) TH_Buf(46) TH_Buf(46)
47) --> Proton Volley==> Acc(47) EndRdx(48) Dmg(48) Dmg(48) Dmg(50)
49) --> Swift==> Run(49)
---------------------------------------------
01) --> Sprint==> Jump(1)
01) --> Brawl==> Acc(1)
01) --> Vigilance==> Empty(1)
02) --> Rest==> Rechg(2)
---------------------------------------------
Seems a reasonable build.
Don't slot PFF. 1 recharge is all it needs to make you almost completely invulnerable.
Is there a reason why you are 3 slotting Hurdle? PvP?
These are minor points below.
From the leadership pool, for a bubbler I'd say slots in Maneuvers are more useful than slots in Tactics. An unslotted Tactics will increase the to hit of your team such that they can hit foes about 2 levels more. The 3 extra slots only increases that by 1. Maneuvers on the other hand gets your teammates so close to 45% defence soft cap that even the last 0.7 defence you get increases survivability a great deal ( about 15% less damage between 2 slotted and 3 slotted ).
Also I'd say than generally Tactics is more useful than Assault so I'd get it first. Assault is a 18.75% damage buff, which in real terms means that your team do 10% more damage. As by that time your force fields are going to allow your team to safely survive about 2 levels higher than without you ensuring that they hit is probably more important.
@Unthing ... Mostly on Union.
Hi thanks for the replies.
I 3 slotted hurdle to help with travelling. Since I am going for superspeed I wanted to be able to jump a little higher to help with travelling between missions etc. Do you think adding combat jumping would be better than having 3 slotted hurdle?
What enhancements can I add to assault? the builder I am using only puts in end reduction 
Hi,
I am thinking of making a bubbler/rad defender and have created a build. Can you please take a look at it and advise on the build. I am aiming to run the build from level 1 to level 50, so will be starting from scratch.
Thanks!
---------------------------------------------
01) --> Personal Force Field==> DefBuf(1) DefBuf(43) DefBuf(46)
01) --> Neutrino Bolt==> Acc(1) Dmg(3) EndRdx(7) Dmg(23) Dmg(37)
02) --> X-Ray Beam==> Acc(2) Dmg(3) EndRdx(7) Dmg(23) Dmg(37)
04) --> Deflection Shield==> EndRdx(4) DefBuf(5) DefBuf(5) DefBuf(13)
06) --> Hurdle==> Jump(6)
08) --> Insulation Shield==> EndRdx(8) DefBuf(9) DefBuf(9) DefBuf(13)
10) --> Irradiate==> Acc(10) Dmg(11) EndRdx(11) Dmg(40) Dmg(43)
12) --> Dispersion Bubble==> EndRdx(12) DefBuf(15) DefBuf(15) DefBuf(19)
14) --> Health==> Heal(14) Heal(19) Heal(43)
16) --> Hasten==> Rechg(16) Rechg(17) Rechg(17)
18) --> Super Speed==> Run(18) Run(50)
20) --> Stamina==> EndMod(20) EndMod(21) EndMod(21)
22) --> Assault==> EndRdx(22)
24) --> Tactics==> EndRdx(24) TH_Buf(25) TH_Buf(25) TH_Buf(27)
26) --> Vengeance==> TH_Buf(26) DefBuf(27) Heal(31) DefBuf(34) TH_Buf(46) Heal(46)
28) --> Cosmic Burst==> Acc(28) Dmg(29) Dmg(29) Dmg(31)
30) --> Electron Haze==> Acc(30) Dmg(31) Dmg(33) Dmg(34)
32) --> Maneuvers==> EndRdx(32) DefBuf(33) DefBuf(33) DefBuf(34)
35) --> Neutron Bomb==> Acc(35) Dmg(36) EndRdx(36) Dmg(36) Dmg(37)
38) --> Atomic Blast==> Dmg(38) Dmg(39) Dmg(39) Rechg(39) Rechg(40) Rechg(40)
41) --> Electric Fence==> Acc(41) Acc(42) Immob(42) Immob(42)
44) --> Charged Armor==> EndRdx(44) DmgRes(45) DmgRes(45) DmgRes(45)
47) --> Power Sink==> EndMod(47) EndMod(48) EndMod(48) Rechg(48) Rechg(50) Rechg(50)
49) --> Combat Jumping==> Jump(49)
---------------------------------------------
01) --> Sprint==> Jump(1)
01) --> Brawl==> Acc(1)
01) --> Vigilance==> Empty(1)
02) --> Rest==> Rechg(2)
---------------------------------------------