rF1 is 10 years old. You are asking a question like which to pick, Far Cry 1 or Far Cry 4. Sims move fast forward and rF1 was built to run on a PC with one CPU core and a GPU with 256 MB VRAM. It hasn't received any notable updates since 2007, whereas rF2 will be updated for years to come.
Until you meet those little beasts... That killed the game for me, I was really enjoying fc1. Good times...
Sorry to be off topic.
Rf1 has tons of cars and tracks for you to enjoy, but rf2 is the sim to go, best physics by far compared to any other sim out there.
You know that does bring up a valid point, if you are running a very old system then maybe rf1 could be better than rf2. However I don't really see a need for rf1 anymore as I feel that AMS is a greatly evolved and refined version. So like the earlier poster mentioned, rf2 and AMS may just be the answer. Plus aren't they both on huge discounts for one more day?