What does everyone like? I need to get a 4 channel amp. Thanks

Alpine PDX.

JL any good? I also need to get a pair of 10" subs. Thinking alpines for them as well

I've used JVC amps for years with good success and great sound. However, I've always used the automotive units mounted in a cabin - over 15 years on two units with no problems when I sold the boat. Went back with JVC on the new boat.

I have JL Audio in my boat. 2 10" subs with 700W sub amp and the 6 channel main amp for the other 10 speakers. Sounds great.

The same here, I always use automotive amps in the cabin. I have been running my Memphis class D hard for years now and no problems.

I have Alpine PDX amps and the Alpine Marine 10" subs.
Get the automotive version PDX amps off ebay. They cost much less than the Marine ones and are basically the same.

I wouldn't hesitate to get the JL digital amps either, but they cost more tha PDX's.

FOCAL. We use FOCAL for all new Outerlimits, the speakers are loud and clear, and the amps are a perfect match for the system. We use JL Subs, but the FOCAL K2 Series speakers are the way to go.

Waves and Wheels in LOTO are huge on FOCAL.

JL and Alpine have always made good stuff, can't go wrong but you do pay a bit of a premium for them. I had Clarion last couple boats and had good luck, have Sony stuff now and like it, they are solid if nothing else.

If I was building from scratch today, prob. go with JL for speakers, Alpine or JL for amps (and Clarion or Alpine for the head unit if you want and / or need a new "marine" head unit).