Seconding Weber.

It's not the only good brand out there. But no matter what type of grill or grill-adjacent hardware, Weber is safe for BIFL.

My Weber charcoal grill is second-hand, from a friend who really didn't take care of it. But even after years of abuse, it's still in great shape without any rust. I didn't even need to replace the grate, just thoroughly clean it.

My Weber smoker is 15+ years old. When a handle on the door came loose, they sent me a whole new replacement door at no charge (since the handle isn't intended to come off).

For this I think the answer is Weber. You can get replacement parts easily and I assume a natural gas conversion kit for any of their propane models. There is a small performance difference with natural gas but it's infinitely more convenient

Weber is a great brand. I personally run charcoal. It takes 30m to heat up, but that’s often enough time to knockout any prep and do a once through on cleaning.

I had a propane grill with a natural gas conversion and hookup at one point. Really nice not having to worry about whether there's enough gas in the propane tank. No discernable difference I could see between cooking on propane vs. natural gas.

I have no idea what it costs to set that up though, that natural gas line setup was already in that house when we moved in. I would have looked into it for my current house, except I'd switched to charcoal before I moved here. Love the flavour of charcoal, but convenient it ain't.

Another Weber vote here. Bought my first grill, a Genesis (E-335 if I’m not mistaken), nearly 17 years ago. I’ve fed it replacement parts here & there, but haven’t had to spend more than $300 on maintaining the thing this entire time.

I've got natural gas, and will never go back to fighting with propane tanks.

Weber is probably your best gas grill option, but spend the money on their high-end line. A fair competitor would be Napoleon.

Alternatively, abandon gas and get a Big Green Egg. It'll outlast your grandchildren.

We have a propane Weber Go Anywhere grill from the 1990s that's still in perfect shape, and we were able to upgrade to third-party griddle cooktops.

Just thought you might want to know this exists - I imagine it might exist in English sites too?

https://varuste.net/en/p46719/muurikka-electric-smoker-1200w

Now you can get smokey flavors if you want to and don't need a fuel source

BBQ grill or kitchen oven grill?

If BBQ I have been thinking the best choice is to just get a replacement grill top for any reasonably decent BBQ and then dry stack some bricks to place it on.