If you buy better power supplies for your computers, you could get away with the cheaper battery backup type UPSes as the PSU itself can compensate for brownouts down to 100 or even 90 VAC in some cases. These usually also have active PFC (Power Factor Correction) and would be top line units in any PSU mfr's catalog.
. But APC, TrippLite, Powerware and CyberPower make decent UPS units - stay away from Belkin. If you don't have a PSU like the above, then you will want at least a "line-interactive" (fancy term for having some voltage compensation to keep things going w/o having to switch to battery) UPS. A step up from that also offers true sine wave output (the others have modified square wave outputs). Another step up has a ferro-resonant transformer that gives linear voltage compensation (the others have several fixed steps) over a fairly wide range before switching to battery and most have true sine wave output - The Best Power Ferrups was the best of these and is merged into the Powerware line). And the top of the UPS line (and really the only one worthy of the UPS label) is called 'full-time' - means that your system runs off battery power all the time and the AC connection is there just to keep the batteries charged, so your system is completely isolated from the AC line. These are also quite expensive and all that I know of give true sine wave power (good if you want to run something that uses a synchronous AC motor or doesn't work well on the modified square waves). Clary is a name that is highly regarded in the full-time UPS field - the others usually make them too (IDK about Cyber).
. Most of the same names also make decent surge suppressors. Plus, if you want the best, there is Zero Surge (zerosurge.com). It uses large capacitors and coils to really absorb the surge rather than switch it to the ground line as MOV (metal oxide varistor)-based suppressors do. Costs a pretty penny and are not widely available, but then the best seldom is.
. I like to have at least 1000 joules of suppression on the AC outlets alone (most UPSes also include a suppression stage and some outlets that are just filtered/suppressed besides the backed up outlets) - some have connections for phone, coax, etc. and add the joule values for each section together. Don't buy any that reports the joule value that way. Good to have some EMI/RFI filtering too starting at a low frequency like 100kHz with at least -3dB drop (cuts the power at that frequency in half) with the filtering rising rapidly from there.
.bh.