You'll get as many ideas as there are detectorists on this one, LOL! You'll find Minelabs to be great detectors, but also spendy. You'll find the Garrett Ace 250 to be inexpensive, but a good little unit for a beginner.
Some say buy the most expensive detector you can afford, some say buy the least. I opt for the latter, at least until you know if it suits you or not. Then get the spendy ones if you get hooked on it, like most of us have.