If you like RPGs the only ones of any consequence on the C64 are going to be Legacy of the Ancients and Legend of Blacksilver
the rest can be experienced with DOS with less of a headache involved. im sure you dont want to swap 5.25" disks every time you go to a new place.
all of the Ultima games with DOS have been EGA/VGA'd and have music now if they had it in the first place so dont let anyone tell you youve got to play it on the C64. They're probably high. The SID music on the C128 versions arent worth the disk swaps.
Wasteland: Same concept. You even get a mouse which makes things easier
Bards Tale: They look like crap on every computer, so you might as well play it on DOS where there's no loading mess.
Wizardry: Its ok, but its no better than any other Wizardry incarnation.
M&M: same as wizardry really. Though I prefer II on the PC
actually, you're going to find that most games in 2009 are not worth loading on the C64 because of disk swapping. DOSbox + PC versions allow you to enjoy the game without losing your immersive factor every time you gotta swap disks
aside from Legacy of the Ancients and Legend of Blacksilver, your other must-play RPGs are Wizards Crown, Eternal Dagger, and Temple of Apshai Trilogy.
the rest (goldbox especially) exist in DOS, and are much more accessible to you.......
so its possible you arent really going to ever get to into the C64 since the nostalgia factor isnt there.
You might have been really into it back when it was new though!. It DOES have alot of RPGs and when it was current, did a great job, but hey! its all ancient now, might as well pick the convenient one...
You can try alternate reality on the c64, and maybe Knights of Legend and Times of Lore, but I am thinking you will try the DOS versions and go "oh, right".
strategy RPG wise, theres some wargames? like war in middle earth and crap, but theyre iffy if you're looking for really in depth stuff. Sword of Aragon for PC, now theres a good one.