I've pretty much played them all that you mentioned at least in one form or another. Instead of boring the populace with a boring diatribe on which was better than others, the fact comes down to this. While impulse buying is awesome for store owners, it’s not awesome to have a lot of stock that you can’t be sure is going to be “impulsed”. There’s a reason that the games that you find at most stores are pretty universal. Those are the things that sell.
I love Rolemaster (you’ve gotta love a game with a critical chart that includes the fumble of slipping on the invisible dead turtle). I enjoyed the old Star Wars d6 rules, heck I was buying the books right up to the day that WEG went stupid and ended up losing the rights. I’ve played Hero System, Aberrant, Battletech, and a hundred and one other games in some form or another. The simple fact is that D&D sells. Warhammer 40K and Fantasy Battles sell. May I suggest, though, Impuse buying Star Wars Saga Edition? If you’ve got old Star Wars books, it’s not too hard to convert. Hehehe… Or Serenity?

I loved the HERO/Champions system back in the day. I still own my original books plus some more recent material. It can get cumbersome with all the dice but it is very flexible. You can make just about anything with HERO/Champions.

You will either love Rolemaster or hate it. I tried Rolemaster once. I have some friends that love it but I refer to it as "Chartmaster" or "Rulemaster." I thought it sucked. It took 15 minutes to determine a single attack. I hear that the game is great if you have degree in physics or mathematics. I don't so I didn't like it.

I have tried D6 Star Wars and Traveler. I liked the D6 Star Wars system well enough but I thought that the published adventures for Traveler were lame and boring. I will give Traveler one thing though. It it the only game system were your character can die during character generation.

As for now, I play primarily 3.5. I have recently tried the Savage World system and I liked it a lot. As a universal system, it runs a lot easier and smoother than GURPS. I am likely going to be running a Mutants and Masterminds game in the next month or so. I would love to try Castles and Crusades but I can't find anyone that plays it.

Sadly, there's very little demand for the "other" RPGs, which is why they're hard to find in a store. I know a couple people that play HERO and occasionally I'll get someone interested in Rolemaster (mostly the nostalgiac types who played it when they were younger). I haven't had anyone ask about d6 games in over a year. The Star Wars RPG has a decent following (the d20 version, not the d6) and is fun to play. I also know of a couple of people who are actively trying to get a group together to play the Warhammer 40k RPG. If you or anyone else is interested in playing the Warhammer 40k RPG, please let me know so I can get you in touch with the rest.

~Gary