You basically have four choices when it comes to strobes (in my opinion). I'm assuming you are talking here about personal locator strobes and not car strobes.
First and newest and one of my personal favorites is Inova 24/7. It has eight LEDs and is tri color. It has 8 flashing patterns including SOS, distress tri color mode (which I use for biking and road work), flashlight mode, etc etc... It is powered by CR123 battery. There were some complains about durability of this bad boy and mine also broke but Inova has been superior in replacing mine. I used to have separate strobes for biking, kayaking, work, etc etc. This is one light in all. Together with next strobe I'm going to mention is mostly all the stuff you need. 24/7 is also waterproof but it is not a diving light. (about $40). They lately came up with load of attachments for this light (head band, magnetic holders, stands). Very cool feature is that you can put the strobe in the find me mode. It will blink very dimmly in red color so you can easly locate it.
Your next strobe is a military MS2000 strobe which basically has 3 modes. IR mode, Blue mode and White mode. It is powered by AAs. I think it is build tough and solid but some people on this board complained about durability of the “blue mode”. Also little disadvantage is that when strobe is closed IR filter is covering the flashing part. If by accident strobe is turned on you can’t really see it and you may be stuck with dead batteries. This problem can be easily fixed by checking your equipment on the periodic bases. Also there were some complains about contact corrosion but again I didn’t encountered the problem on my strobe. There is also a version of this strobe where flashing patter can be turned off and unit can be used as a regular flashlight.
Your third choice is Princeton Tec Aqua Strobe. This is mostly designed for kayaking and diving. This particular light stays on my kayaking vest. It uses single AA battery and will run about 8 hrs non stop. It has only one pattern. It is really durable and strong.
Last but not leas is going vintage. Air force had their own survival strobe SDU-5/E before replacing it with MS2000. Problem is that that strobe was using special 3 volt (I think) battery that unfortunately can’t be obtained anymore. Few guys on ebay designed a special extension or cap that fits into the body of the strobe and allows you to use 2 CR123 lithium batteries. Now I’ve tested this strobe few times and it’s a decent piece of equipment. You can purchase addition parts like lenses for pennies. But disadvantage of going this way is that equipment most likely has been used, if it fails you need to replaces it since there is no warranty. I have it in my car as a back up strobe.
Hope that helps,
Matt