I had a 3000 Watt AIMS PSW inverter. The positive and negative terminals are basically a nut and a bolt. The nut holds on the positive terminal bolt in place came off, rattled around inside the box, shorted stuff and fried the unit. Prior to being fried, it worked perfectly. I had one on the houseboat that worked perfectly for years, but on a houseboat they don't take the same kind of beating they do on smaller, faster watercraft or on board expediter vehicles. I know other expediters who have had their AIMS units fail way sooner than they should. I'm thinking the AIMS units are fine, but aren't very rugged at all. RLENT had to return his for replacement 2 or 3 times, I think.
Xantrex (PROsine, not PROwatt), Go Power (also branded as Carmanah), Outback, Charles Marine, are all good brands for PSW inverters. Solid, rugged, few complaints, good warranties. You want at least a one year warranty, two is better.