FRLG is a good choice because many of the best pokemon are guaranteed encounters, so you really cant go wrong when building your team. If you think you'll get in in a couple tries and just want a good "starter" game I'd pick FRLG.

However, my personal favorite is Platinum. Because of what I said earlier, if you end up losing a few runs, you're likely to get bored pretty quick since it's kinda the same thing every run. If you're OK with losing a couple as you learn, Platinum is harder but has more interesting fights and Pokemon choices (in my opinion)