Ron Zacapa Solera 23 is probably the most common and certainly the one I see 'in the wild' the most often. It's a mega-corp rum (Diageo) and bit looked down upon by many rum snobs, but it's pretty good and a decent enough place to start in my opinion, and you shouldn't have much trouble finding a pub with a bottle behind the bar if you just want a taste rather than buying a whole bottle.
I quite like the Ron Zacapa but someone coming from the whiskey world should know that the 23 refers to the oldest rum in the blend and not the youngest like you find in most whiskey. They are quite upfront about this on their labelling, but it did take away some of the "how did this price descrepency happen?" for me.
Very true, just to muddy the waters further however bear in mind that maturation generally happens at a faster pace in hotter climates which rum producing countries generally are.
This might just be the booze snob in me talking, but I think Ron Zacapa 23 was significantly better up to about 5 years or so ago. It's still good, but I think increased demand/production has resulted in an inferior product compared to what it used to be.
Try the Santa Teresa 1796. Highly recommended and still my favorite after many years. I'm biased though, since it's Venezuelan (and I am too).
Try Dictador 12. Shouldn't be too expensive and is widely considered to be excellent.