To be fair, the third one was horrific, my only craving for it can be justified as childhood nostalgia. The first one however was very different, it was actually more or less independent from the sequels in terms of game mechanics and graphics.
I believe I saw some screenshots of a similar game in the GOG cataogue but I cannot remember which one it was. The game had fantasy RPG elements( weapon upgrade, magic levelups, different character types ect) , a large variety of dungeons, it heavily relied on exploration ( with the occasional miniquests too) and could be very (but not frustatingly) challenging. I found an example of it on youtube:
http://www.youtube.com/watch?v=7zM4wldrN14&feature=relatedwpegg: I remember buying Lands of Lore 3, and finding it so bad it is the only game I have ever returned to a shop. They allowed me to exchange it for Silver, which was so much better. So I'm afraid I don't share your love for the series.
Having said that, I've heard a few people crying for it. What in particular are you looking for in a similar game? There are a number of cRPGs around on here (that's how I'd classify 3, haven't played the first 2), what really made it stand out for you?