Well from that list if this was pre i13 pvp I'd say Necro/TA hands down. But in light of TAs swift shot to the gut in i13, don't waste your time.
Second choice would be Merc/Poison for pvp reasons. For PvE I'd say Thug/Storm, does pretty decent in pvp as well.
Robots/Traps is an absolute beast in PvE, and will definitely help a team (for one thing, they make excellent tanks if you take Provoke). Robots/Pain is even better for team support but you don't have that on the list. However, you may not want to focus on the Bots/Traps for IOs simply because they can do so much without IOs, including soloing archvillains. Thugs/Storm, on the other hand, would benefit enormously from IOs and would also be a beast, and it might be better in PvP (I don't PvP so not sure). Of course if you want absolute domination, fully IO out the Bots/Traps... then your team contribution on an ITF will be the ability to solo the entire task force, so no matter who drops out your team can win. 
(It'll probably take a lot of practice, but Bots/Traps is one of the few builds I've heard of soloing the ITF.)
My rankings for solo would be:
1) Bots/Traps
2) Thugs/FF (safe but slower)
3) Thugs/Storm
4) the rest, not sure of order
Keep in mind that any Mastermind solos well though. If you want an AV soloist instead of general soloing then /Poison is good, but for general use it's a bit iffy.
For teams, it's more about the secondary.
1) very well played Storm
2) FF, Dark and Pain (all are good, FF less so for AVs)
3) reasonably well played Storm
4) TA
5) Traps (move it up a couple spaces for AVs)
6) Poison (move it up a lot for AVs)
7) badly played Storm
As you can see, Storm is highly dependant on player skill...
As for fun, that's pretty subjective. I personally like Bots/Traps best because I love being able to solo anything I run into, and when I do team the massive AoE laser show never gets old. I also like Storm for the pure chaos of it... but more so on other ATs for some reason.
Cascade, level 50 Blaster (NRG/NRG since before it was cool)
Mechmeister, level 50 Bots / Traps MM
FAR too many non-50 alts to name
[u]Arcs[u]
The Scavenger Hunt: 187076
The Instant Lair Delivery Service: 206636
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Necro/Trick Arrow Level 36
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That should be a good challenge for ya! I am a bit like you who want to be different sometimes. I have yet to see a Necro/TA. I may have seen it below lvl 10 but definitely not 40+.
If you are bored, you need something very different and sort of challenging.
I suggest Necro/TA.
Judging by population, Ninja ranks the lowest followed by Merc.
You can try Ninja/Poison or Merc/Poison too!
What's left is to normalize all Assassin Strikes and improve Stalker's old sets (Claw, MA and EM)! You don't need to bring back the missing PbAoE attack. You just need to make the existing ones better! For example, make Slice a WIDER and LONGER cone.
I love my masterminds. I have been a victim of altitis for a long time now, but I am finally finding the game growing boring for me. Ive run out of alts I want to make, ATs I want to try, etc. I have found nothing else in the game comes close to a mastermind for the way I enjoy playing it. I have eight active masterminds, and I am looking to focus primarily on one. The levels dont matter- if its lower level, I will work my way up. If its high level, I still have plenty of invention salvage gathering to do. Below Ive outlined some of what I like about my MMs and what I hope to be able to do- based on that, and your own thoughts, please shed some light on which one of these masterminds you would suggest as my best bet for this focus. Im very interested in the communitys thoughts. My only stipulation is, I really want it to be a Mastermind. I realize based on the below categories that there are other ATs that can do what Im looking for better, but what Im really after is which particular Mastermind can best fit this grouping. Id prefer it be one of the builds I have already established, but if you think I simply HAVE to have a new build of an MM, I would consider that. What would be really great, if you feel so inclined, would be a ranking of the below in terms of the various categories- (solo, team friendly, high end strike forces, fun, etc) Thanks for any and all responses! (my criteria and thoughts below)
Robot/Traps Level 50
Thugs/Force Field Level 50
Mercs/Poison Level 37
Necro/Trick Arrow Level 36
Ninjas/Dark Level 26
Ninjas/Pain Level 25
Thug/Storm Level 24
Necro/Poison Level 18
First and foremost, I like to solo. I dont have any hard and fast rules, but sometimes, I just want to solo. I enjoy redside more than blue- this has been debated quite a bit, but for me I would rather be bad. I like being able to help my team. Even though we MMs cant keep up with Defenders, Corruptors or Controllers, I feel like we can bring a lot to a team. Ive found the more people on my team, the less my pets matter- but the buff/debuff makes me useful regardless. Finally, I like being unique. As the only AT with access to the pets powersets, I feel like I stand out. (And thankfully, there arent QUITE as many masterminds running around as there has been in the past.) Not to mention nothing feels quite as stereotypically villainous as ordering others to do your bidding.
I am looking for a main villain, for a couple of reasons. I dont enjoy the inventions process, but Ive decided to give it a go. I only plan on doing it for one toon, however. On the off chance I want to PvP, it will be with this mastermind. And since masterminds are my favorite AT, I feel most comfortable here. There may be other ATs that outshine us (Im sure there are), but Id rather make the most of what I like. Lastly, I want to be able to participate in the end game stuff. ITFs, LRSFs, etc. I realize Brutes and Corruptors basically rule this villain side, but surely there are MMs that are found to be useful during these high end tasks.