Tough questions for this format, Hugh. Each paddler has his biases.
Good names St/Horizon, ICOM, Humminbird etc
Cost depends on what features you want. Some features are frills, in my view.
Where to buy – locally Steveston Marine at 3 locations esp if offered on sale.
Must have waterproof rating
must accept regular AA batteries as well as having NiMh not NiCd battery pack. This usually means having 2 battery trays. Also must have Weather Wx channels but I think this is standard, 3 yr warranty
Nice to have – battery strength indicator, dual watch, channel lock
Not needed but not bad either Dig Selective Calling, GPS, tri channel watch, scan, floating
5W vs 6W not material
battery life – specs tell some of the story but unbiased reviews are better. Want good standby (receive mode) life. Adding features reduces battery life. Turn off gizmos for decent battery life – usually one day, maybe two. Turn off radio for extended trip or have some means of charging or use many, many AA batteries Can be rechargeables, but they have shorter battery life.
I would normally use a radio bag and not rely on the waterproof rating which depends fully on the radio being regularly rinsed with fresh water (you could carry an extra few litres of water just to rinse your radio I suppose!)
See quite fancy S/H HX 870 $285 on sale at Steveston but probably comes without AA battery tray. Too many features in my view, so look downwards from there. Should get a nice one around $150.
Most are sold to boaters who leave them in on board chargers 90& of time and use them just for shore trips in the tender. Hence battery life has been sacrificed to compact size, convenience somewhat, to suit that market.
I can’t comment on various ways to charge your NiMh batteries on long er trips – i suspect the wall wart chargers make the whole process too inefficient to contemplate so it is nice if the radio is chargeable directly from say a 9 -12 V DC source. Some are.