recently had the same choice...and 500 was also my price point.
I do have a decent lab but am trying to reduce the form factor and be a bit more efficient. A modern digital scope defiantly does that as it also performs measurements you might use other equipment for if you were using a CRT based scope, or might take you extra time and effort to do. So, if you're not going to buy tons of equipment, a digital scope is a really good starting point in today's world. .. least that's my view. some many will disagree. a CRT based scope is a good and cheap way to learn the ropes, but, frankly if you have the budget, why not get what is basically an all in one tool.
i went with the SDS1104X-E, the added bonus is its hackable to 200mhz. really was a no-brainer for me after digging into them both a bit. I really didn't need 200mhz, so, id been quite happy with 100mhz. with the rigol, it never sat well that id need to hack it to get to my minimum expectations. it's just nice that I can get 200mhz out of the siglent.
the downside is the logic analyzer isn't all that great from all reports. so id not make that a heavily weighted factor. I'll likely go for an eBay usb logic analyzer if I need one in the short term until they refine the add-on spectrum analyzer for the scope. give them time, i am sure it will be good. just not today.
The SDS1104X-E simply out classes the rigol DS1053Z. I'll let the specs speak for themselves.. check this thread.
https://www.eevblog.com/forum/testgear/siglent-sds1204x-e-released-for-domestic-markets-in-china/and as far as 2 channel vs 4 channel, well with the 200mhz hack, there's no point in getting the siglent 2 channel model.
there is plenty of hand on reports out there to help you make a decision, defiantly read them.