I used to use TINA-TI a lot. I like it more than LTSpice as it lets seeing plots from previous simulations. It seems to be dead now. I don't like ltspice UI (for many reasons), so I was looking for other simulators, but I'm on Linux, so my choice is limited. I think I tried pretty much everything worth trying, including paid software.
My choice would be TINA if they had better pricing. I tried their cloud-based version. It was cheap (I think below $20 per year), but buggy and slow. So, don't recommend (unless they improved it, I tested it two years ago or so). TINA 10+ also got many new features beyond simulation, like pcb design etc, they were unusable when I was testing. Also some Linux-related problems (although they don't officially support Linux).
QUCS didn't work for transient response analysis. There was a fork attempting to fix it, not sure if it's still alive and/or changes were merged back into original QUCS. UI is also non-intuitive, but that's a problem with most simulators. At least some knowledge about SPICE is needed (that's true about many other simulators too).
There used to be a free version of pspice, dut I wasn't able to get it running on Linux.
https://www.falstad.com/circuit/ is a good choice for very small circuits, I use it sometimes. Afaik, it's open-source and it's possible to download it and run localy, if needed.
There are other "cloud"-based simulators. I tried them all a couple of years ago, none made me happy. Some had horrible UI, some had ridiculous limitations and paid subscriptions, most of the don't let exporting design (imho). May be things are different now, Idunno.
So, what I'm using now? Ltspice, it runs smoothly on Linux. Usability is questionable, learning curve is steep, range of available components is limited to what the developing company sells on the market, but I don't see an alternative for Linux users.
Anyway, no matter what simulator is chosen, there is a learning curve. And don't blindly rely on any of them as they are as accurate as underlying models are. Also, keep in mind most simulators don't warn you when exceeding absolute maximum ratings, temperature, etc. There are many other aspects to keep in mind (ambient temperature, self-heating, tolerances, parasitic effects, etc) when using simulators.