I use ATT prepaid, which IIRC means I use the same towers as Straight Talk.
I have one particular friend who I sometimes get messages VERY late from, and they also sometimes immediately repeat themselves anywhere from 3 to 10+ times. I had chalked it up to his house somehow being in a tiny blackout area...he's in the same neighborhood as me, but is in an area that's surrounded by woods, with a big hill on one side. It's always hard to get reception there, even though it's in the middle of a dense suburban area that is otherwise fine. But then...I confirmed it happened while he was at work in a totally different area, too.
He's on ATT proper (monthly/contact). It happens to no one else that I regularly text with. Very weird.
I also have issues with MMS messages sometimes refusing to send (not limited to one person). I have just accepted all of it as a product of shitty design in the SMS/MMS system...the phones don't really 'handshake' like they do with a call. Once a message is confirmed 'sent,' its in the network's hands to make sure it actually reaches its destination.
Yet another issue I have is with the time (as 'provided by network) randomly lagging behind 5-10 minutes or more, and never syncing back up unless I force it (disable/re-enable auto time and/or restart phone). This forces me to set the time manually, which is never QUITE perfect, so rapid-fire messages end up out of order.
Blah, modern cell phones are shit. [edit: I use a Samsung Captivate Glide, which is an oddball phone on the Tegra2 platform...gotta have my damn physical keyboard, dammit]