online ups or inverter with normal ups?

An online UBS is going to be better though more expensive - with a cheap offline one you will get a brief glitch.

The issue of whether to have a generator as well is a separate issue. A UPS typically provides power for only a few minutes, maybe up to an hour - time enough to finish what you were doing, power down computers gracefully etc.

Any UPS normally includes an inverter to make AC from a DC battery, unless you have some ancient flywheel motor-generator setup.

I think you actually mean "inline UPS" not online - as with the internet. And I think you will find that the inline UPS (basically a generator running all the time) that the cost of operation is very high compared to battery plus inverter and if you can isolate the operations that are critical (usually a small proportion of the actual power) you can continue to function without the large extra expense of a full time backup.