PT100 v PT1000 - which to use
Pt100 has lower resistance and probably is better for industrial situations with EMI.  The leadwire resistance is more of a factor and 3-wire connection is usually used (4-wire for lab type applications, it's rare in industry). Leakage due to moisture etc. is also less likely to affect the reading substantially. It's also the most common standard (which came about in part because of my 3rd point, since reasonably accurate thin-film RTDs are a relatively recent development). 

Pt1000 can be used 2-wire in many cases because reasonable leadwires are relatively low resistance. 

It's pretty impractical to make a wound-wire RTD of 1000 ohms so they are generally of thin-film construction, with all that implies. If it could be made it would be even more bulky, slow and fragile than a 100 ohm wound RTD. 

Self heating is proportional to the output in either case, so it's a wash, but you need less current for the same output with a Pt1000 (perhaps a factor in loop-powered instrumentation).