Depends I guess on how you expect to use it.

My Experience:  We had an 8' Baltic inflatable which was great.  Price has gone up, we paid around $500 to $600 as I remember.  Painted the bottom with dinghy bottom paint and left it in the water all season.  Brought it home in the winter. I let it go when we sold that boat.

Now we have a used 10' Zodiac Zoom that I picked up for $400.  It has davits already on it.  10' is much more room for my wife, 110lb German Shepherd & me.  This winter, I've dropped 2 lines over the stern to grab the davits and lift it up perpendicularly out of the water.

On both dinghys I use a 9.9hp 2 stroke Mercury which I bought off Craigslist for $700.  I love it!  It gets both dinghys up on a plane, which is a lot of fun after putting along (or sailing) at 5 - 6 knts all day ;-)

My two cents worth, I have a Caribe 11 which I have had for about 10 years now. It flipped off the trailer the 2nd year I had it and that is the only physical damage over the years that is visible. I did not bottom paint initially but the growth forced me into it. It is a hard bottom and holds 4-5 very comfortably. I have a  Mercury 8 HP 2 cycle which will allow the dingy to plane with me in it, alone. I had a 9.9HP  4 stroke Mercury which gave me a lot of starting issues, ethanol gas probably the main issue plus the compression of the 4 stroke. The 8HP is heavy, but not as bad as the 9.9. I for the most part tow the dingy and with the bridle I rigged it does not affect speed too bad even under sail.

After a lot of thought about how we use a dinghy, we settled on a 9 foot AB rib with an aluminum hull.  I think it only weighs 70 lbs.  I installed a folding pad eye on the foredeck and for longer passages or rougher weather we use a spare halyard to winch it up onto the foredeck and lash it down.  Because we are lashing the front of the dinghy to the pad eye and the aft end to the handrails storing the dinghy here doesn't impede movement to the foredeck and there are no lines crossing the deck to be trip hazards.  In lighter air I just tow it with a bridle and towline made up from floating polyprope.  We settled on a 6 horse 4 stroke.  Anything larger (8-9.9 hp) uses a larger engine block and adds about 20 lbs.  I also have a Garhauer engine lift to handle the outboard.  This is a great product!  We always remove the outboard when towing.  The 6hp will only plane with one person on board, but pushes the dinghy along at a very nice speed with 2 of us.  This size will handle 4 adults, but it is a little tight.
Regarding the fourstroke.  3 years after buying a nice new Merc I had problems getting it started.  A trip to the mechanic resulted in replacement of the carb.  You cannot access the jets to clean out the crud from ethanol fuel.  Since then I have sought out and use nothing but ethanol free gasoline.  There are several websites that will lead you to stations where you can buy.  Given the small amount of gas we burn each year its been a pretty good investment.

Very difficult to answer unless you know how you intend to use it.

Lost a 10'4" Achilles Hypalon Inflatable floor - it was really nice.  Lost it overnight in taking some water over the deck.  Never underestimate the power of water.  This was a nice dinghy and pretty stable.  It would have stowed really nicely down below.

Now I use my old RU-260 from West Marine and a 2.5HP Honda.  Really only works for 1-2.  If there's chop it's a wet slow ride.  The plus? It weighs all of 40lbs and can easly be stowed below and manhandled on deck.

I intend to replace with a Hypalon Dinghy and am torn between inflatable floor and RIB.  My friend bought a AB 9' RIB with a 9.9 and loves it.  Pricey but really nice.