Midazolam is another good rescue drug
We used to use Diastat. For us, the decision to switch to midazolam was easy, Diastat quit working for my daughter. However back when Diastat did work it would negatively affect my daughter for 2-4 days (cranky, coordination issues, etc.) after using it. Midazolam only negatively affects my daughter for 2-4 hours. This is what I like best about midazolam. Administration of intranasal midazolam is easier and quicker than rectal Diastat. It also doesn't hurt that midazolam costs tens of dollars vs hundreds of dollars for Diastat.
I don't understand why doctors prescribe Diastat instead of midazolam. Maybe since Diastat costs so much they get a kick back for prescribing it?
Note that I've only used midazolam intranasally (and once intramuscularly). I now know how to give it intrabuccally, but my plan now is to keep using it intranasally and give it intramuscularly as a backup plan (in case I can't give it intranasally).
If you want a longer more detailed argument for intranasal midazolam you should read this URL which I'm not allowed to post.

Google for "Treating seizures with intranasal medications" it should be one of the top hits. Its address starts with intranasal DOT net. The whole page is a good read, but here's one relevant quote:
"All these authors conclude that trans-mucosal midazolam is more convenient, easier to use, just as safe, and is more socially acceptable than rectal diazepam. Furthermore, when given via the intranasal route, midazolam is more effective than rectal diazepam."
From that site it looks like the order of preference (from most to least preferred) for midazolam delivery is:
1. Intravenous (IV) (assuming you can quickly start an IV)
2. Intranasal (IN)
3. Intramuscular (IM)
4. Intrabuccal (IB)
The hardest part about getting midazolam is figuring our where to buy the syringe/atomizer. We get the “MAD130” syringe/atomizer combo (includes plastic tip for drawing the midazolam out of the vial) from LMA. This website has more details, but I'm not allowed to post the link.

Google for "LMA MAD Nasal Intranasal Mucosal Atomization Device" to find the page.
I'm not aware of any advantage to Diastat over midazolam. My understanding is the lorazepam is more powerful than midazolam which is more powerful than diazepam (Diastat). I've got no experience with Carpuject, so I'm not sure if/how that'd change this equation. Lorazepam is usually only given to older kids and adults that need a more powerful rescue drug. I believe lorazepam needs to be kept refrigerated, so that's one downside to using it.