My addiction isn't strictly BattleTech. I see a figurine that I like, and usually I think 'This would look great painted'.
A lot of Fantasy Flight stuff would look good painted. I've made small dents in my Star Wars Armada fighter and small ship collection. I thankfully haven't really started on the figures of the Rebellion board game, but it will look nice to see all those storm troopers in black and white.
I've started working on the heroes and some of the more common creature groups from Descent, journies in the dark. These and the BattleLore figures all have multiple uses, too.
Having playtested the Robotech RPG Tactics, I have a couple starters worth of stuff that I want to finish up (especially the Zentradi) so that I can finally do games for a campaign I have in mind I'm calling The Chicago Incident, and showcasing a BattleTech compatible anime combat system.
I grew up with a few Megaforce die-cast tanks. These suckers are a great entry point for war-gaming, and I've been hunting down to fill in a good platoon's worth of each of the twelve, plus any of the Mega mobile structures that were the real fun part of the toy line. They have wonderful detail, and a simple wash plus tread treatment is all that some need to be play-ready. Use those for modern-style tanks and armored equipment for said anime style combat, and I'll be good to go.
I have a copy of Centurion that came with 15 grav tank figures to a side. While the person who had it last did an admirable job of painting them, I want to redo the ToG tanks to look more akin to what you find with Star Wars' rebellion ships.
Thunder Road car teams are detailed enough they will look good painted up.
And, then, there's all the variations due to fixation with scale. I've actually picked up Star Wars Risk as well as a friend's beat up Star Wars BattleShip game and some of these funky game cube things you can get from Target, all because Fantasy Flight's CR-90 Tantive IV is not to-scale with the fighters and smaller large ships, like the falcon. I wasn't sure if I'd ever be able to kitbash one that's more appropriately scaled, or that the Collector Toy would be close enough, let alone if I'd ever find one. (I did find one, and it's close, but got some issues.) So, I've been kitbashing a fleet of TIEs as well as X-Wings. Thanks to the BattleShip game, I have passable Bombers and A-Wings, and all I need are a couple Micro Machines B and Y wings to fill the gap in the Rebel Line-up. Just to fit the scale closer to 1/500.
I found that my dabbling in Heavy Gear by their Armada line, as well as my two Jovian Chronicles purchases, they're closer to 1/500 scale as well. That prompted me to pick up the BattleForce Scale Mechs for proper cross-over visual appeal. I've found that many BT vehicles work better at this scale, too, volume-wise.
Same issue with my collection of Star Trek Attack wing. Didn't like the schizzophrenia of scale. Found two scales that I like, though a third is possible thanks to EagleMoss and Micro Machines. But, because a lot of ships come closer to it, I picked up some of the Revel 1/2500 scale models to work with the ClickTech Klingon Birds of Prey and Jem Hadar attack ships.
While I like the Kurita BT Infantry that I've amassed, I've found that they're very setting specific, and I wanted something to run more generic factions in. Most stuff is geared toward smaller 1/300 and looks funny next to cars and tanks of the 1/285 or 1/250 nature. Dark Age Infantry are generic enough and just a touch large, but it's easier to imagine it's the gear bulking them up, along with steroids and foot-ball athlete levels of training. So, I've been working on those.
And, I dabbled a little bit in Epic 40k enough that I've modded what few Orks I have so that I have a propper couple WarBosses, and some recognizably different Nobbs for when I have that cross-over battle.
Finally, I will leave you with a shot of my still growing and morphing Map Scale figure collection, which I've been bashing together for a few years and painting up. This is thanks to Dark Age Infantry and other bits from the plastic mech line. I wanted something to show the true scale of the game. Figured they'd never make the unseen, but I might be able to convince IWM to make sculpts for the stuff that is free of copyright issues, and it bloomed from there.