How so? Signal supports Android and has a cross-platform desktop app (that supports not only macOS, but also Linux and Windows), while iMessage does neither. Signal also has perfect forward secrecy, while iMessage does not.[1] Signal even allows everyone to create and publish sticker packs free of charge,[2] while iMessage requires a $99/year Apple Developer subscription to do the same.[3] I suppose Signal doesn't let you create Animoji or Memoji, but that's not essential to me.
I have been using multiple Signal groups with different sides of the family for a few years now. Honestly, I have yet to run into any problems and few of the groups have roughly 25-100 new messages per day.
Signal isn't that great, but it has cross platform which isn't insignificant (even for you, don't you want to be able to switch computing platforms without losing everything?). However Telegram just blows them all out of the water with the UX, DX, search, stickers, polls, etc.
[1] https://eprint.iacr.org/2021/498 (page 19)
[2] https://support.signal.org/hc/en-us/articles/360031836512-St...
[3] https://www.theverge.com/tech/2016/9/23/13005160/imessage-st...