Best tools for character sheets?

For online-usage, nothing will ever beat spreadsheets. They exist to crunch numbers and compare values. They work with both text and numbers. And they're flexible.

• Want to add +2 to perception for elves? Check if race = "Elf" and if so, add +2.
• Want to add a fixed list of weapons for the player to choose from? Stick the entire list on a secret sheet, then reference them in a drop-down menu.

If a bespoke tool ever came out, it would only do one system, badly. Spreadsheets do any system, and the skills you learn with them are transferrable to almost all other spreadsheet programmes.

There's my indie RPG character spreadsheet (requires Libreoffice Calc). Fill in your name, and it'll use numerological constants to find your race and stats, then tracks your XP every time you buy a skill.

People want to use something like a pdf because it looks like paper, but this instinct is wrong. PDFs are for printing. Their fill-in text boxes are ugly, and programming them is clunky.

Spreadsheet is visually flexible and understands math. Apart from editable pdfs created for the system, I don't think there is something better. Even solutions "for this system but different flavor" will either require of you a lot of input for it to understand the concepts or will be dumb and won't provide more value than a text document

which system are you specifically looking for? I dm for 5e and really like Fastcharater. I mainly use it for NPCs though, so i've never really tried editing them so that might be a hangup.

I generally go

• Preferred VTT
• Other VTT

I like VTTs as I often have visual aids (ex trackers and clocks) and it us a place to share visuals (drawings, scene art).

• Someone's spreadsheet
• Own spreadsheet

Beyond this I don't expect any functionality beyond the most basic things

• PDF sheets on shared drive plus a dice roller
• Discord bots

I generally go

• Preferred VTT
• Other VTT I like VTTs as I often have visual aids (ex trackers and clocks) and it us a place to share visuals (drawings, scene art).
• Someone's spreadsheet
• Own spreadsheet Beyond this I don't expect any functionality beyond the most basic things
• PDF sheets on shared drive plus a dice roller

As others have noted, it depends on the system. VTTs are often thought of as being oriented around battlemaps and visual aids, but you can play theater or the mind with character sheets in a VTT. If the system support is rich like pf2e in Foundry, DnD5e/SWADE in Fantasy Grounds, or any VTT with strong support for a particular system... then you'll have access to great sheets, combat trackers, and automation.

For niche systems, yeah... spreadsheets are the original tool for non-programmers to track stats and math. They're great for building custom sheets. They don't have the flexibility of a true programming language to create custom UI and really rich automation. But they are very very good, and can be better than a VTT with poor system support if you don't care about visual aids.