"In what situation would you use which Routing Protocols?"
There are both technical reasons and other considerations in choosing a routing protocol, the latter sometimes considered more important than the former.
For example of the latter, as already mentioned by another poster, choice might be based on what staff is used to supporting.
Another reason is what the equipment will support or the cost of additional licensing fees.
From a technical standpoint, RIP or RIPv2, are most applicable to "small" networks. Those protocols are often "free" as often included in a basic software package for a device capable of dynamic routing.
From a high level, OSPF, EIGRP and IS-IS are all equivalent, more or less. IS-IS has some feature useful to ISPs, but might not be available on "Enterprise" devices. EIGRP is Cisco proprietary, although Cisco has finally released some of it for non-Cisco use. Unsure whether you need to license that usage, and I believe (?) some EIGRP features are still restricted to Cisco platforms only. OSPF if often used as the non-Cisco proprietary routing protocol when you need or want something better than RIP/RIPv2.
As already mentioned by others, BGP is generally used when you need to deal with really, really large networks, like the Internet, although it might also be used when you want to "manually" manage your network, as it has lots of "knobs" for that.
