I want to second all recommendations of SwissMicros. I own DM15L (~$150), DM41X (~$220), and DM42 (~$250), and they are all absolutely excellent specimens. Not a single complaint. They are easily user serviceable, they have a very high build quality and feel like they will last decades (matching modelfkeyboards dot com build quality). The DM42 has a user-enabled N-stack so you can input algebraic expressions of any arbitrary length. The DM15L is an advanced calculator you (or at least I) can grok completely end-to-end, and packs it all into a compact form; I actually prefer to grab the DM15L before the DM42. The DM41X is also an excellent specimen. It includes the ability to {,un}load module files which are dumps of the old HP-41CX module cartridges. I love every single one of them, and cannot shill (for free) SwissMicros enough. You've beheld Swiss watches, now behold a Swiss calculator!
The hp-50g is pretty nice (I know I know, unpopular enter key location), its USB power and SD card make it quite convenient. Of course the screen is the same as before, but the CPU is faster afaik
And then of course there are many HP calculator emulators and others for android
The 50g screen has only slightly (131×80 vs 131×64) higher resolution than the 48G series, but it has vastly better contrast, and, thanks to improved fonts and other UI improvements, the built-in software on the 50g also makes significantly better use of the limited screen real estate.
N.B.: Meta Kernel[1] provides many of the 50g UI improvements on the 48GX — 49g/50g OS is based on Meta Kernel — but installing Meta Kernel in RAM requires a memory expansion card that, at current used prices, costs nearly as much as a used 50g (plus a steady [semi-yearly IIRC] supply of CR2016 coin cells to sustain the RAM card when the calculator is powered off).
While I also prefer the aesthetics and keyboard layout of the 48 series, the 50g with its bundled software suite stands as one of the most hacker-friendly handheld computing devices of all time: while documentation and development tools for the 48 series were widely available, it wasn't until the 49g that self-hosted versions of these tools (System RPL (de)?compiler, Saturn (dis)?assembler, library creation and extraction tools) were bundled with the base OS.
I'm guessing that you have newRPL. Have you tried putting DB48/DB50n firmware on it? That does have graphics (and RPL). I haven't had time to get familiar with mine, so I can't comment further on capability.