IL-28 is probably the least useful out the lot being larger, slower, lower ceiling height(40k ft), two 23mm forward facing guns and rearward facing guns and 3,000kg bomb capacity, they would be more suitable for bombing buildings, or large convoy's where threats AD are low.
Su-7 wasnt the greatest design of fighter bomber, but did carry up to 2000kg bombs, and X2 30mm guns, a reasonable speed for bombing, decent range, and surprisingly a high ceiling height of 57k ft. These would be suited for bombing and gun runs on light armour convoy's such as IFV, APC, light tanks.
The MIG-19 as previously mentioned the higher speed of Mach 1.3, good ceiling height of 57k ft, a small 500kg bomb load, and x3 30mm guns the guns would be ideal for troops and light vehicle convoy's, even light armour such as IFV would be vulnerable roof armour in vehicles tends to be the thinnest part of the armour (almost rear). So the tactic maybe be better to approach the convoy from the rear staffing gun runs across the rear and roof of the vehicle than front and roof approach. Only real downside to the MIG-19 is it range.
The MIG-17 armed with 500kg bombs, x2 23mm guns, and x1 37mm gun, as above ideal for staffing runs.
The MIG-15 armed with 100kg bomb load, x2 23mm guns and x1 37mm guns same again staffing runs.
The latter three aircraft, are more suited for ground attack roles these days than interceptors/dog fighters, unless up against helicopters, drones, transport aircraft or basic light attack aircraft. Staffing gun runs are there key tactic and most useful weapons. The slower speeds ideal for bombing, but fast enough to make a quick break away after attacking, and their ceiling height, agility and small size goes in favour from basic AD systems such as AA gun fire and basic MANPADS, although equipping chaff would be a good idea as a basic defence. They should be fairly basic to maintain and run. And could be the difference between an enemy advancing on your position or not, or giving your advancing troops an additional fire support via air attack, or disrupting enemy convoy's and supply routes, and freeing up more capable aircraft for more sophisticated air missions. Use what you have to the best of its use strategy. I certainly wouldn't want to be sitting in a vehicle when a small squadron of these old birds come swooping in and screaming down a hail rounds, firing a decent amount of rounds down on you.