In terms of being solid, from best to worst:

Beam mounts
One piece metal mounts
One piece plastic mounts
Interlocking 2-piece mounts
Individual 2-piece mounts

Practically speaking, they all work well if you use them properly. You don't need vibration isolation for engines in the range you're talking about.

The best bet if you think you might be swapping engines in the same range is the two piece inter-locking mounts because you don't need to drill new holes in the firewall, but you may need to replace the mount if the hole for the old engine would weaken the mount for the new engine. Sometimes you can use the mount you already have and sometimes you can't, but mounts are cheap, so that's the least of the problems.

If you use a one-piece mount and decide to swap engines and the new engine won't fit the old mount, then you usually have to do surgery on the firewall which includes putting in new blind nuts. Sometimes that's easy and sometimes it's a real pain.

More about Engine Mounts

- Paul