Off the shelf i'd say a nikko or T50. I hear about variations in the nikko that might want me to take someone who knew what they were looking for if that was the choice. If you go to a shop you can rifle through their stock and pick one
I haven't seen many t50's but the ones i looked through ages ago i'd be happy to use.
Of course, if you want 2nd hand then there's a whole host of options... but i think for a newcomer, you're looking for something that can focus close down, tell 55 & 50 apart, and you know can do the job.
2nd hand i'd not discount the custom shops or debens, but make sure you have a good one, not one that's been fiddled with or is worn out.