I've always liked the Master Grade Line of Gundams made by Bandai. Specifically because they are just the right size and their price is within reach. Add to that the level of detail and parts that they have equates to long hours of model kit assembly fun.
Its probably the reason why Bandai has a lot of kits in its Master Grade line, knowing that there will always be a market for these. Before, when starting out with Gundams, I always looked at the catalog of online hobby stores to guage which kit to buy. Only when I found this great list of Master Grade Gundams at the Bandai site did I realize that there were a lot more MG's to be had out there.
My top two favorite MG's are Char Aznable/Quattro Bajeena's Hyaku Shiki and Rick Dias.
This list will definitely come in handy for me in the near future when I try to rack up my Gundam collection.