Depends on how much credits you got.
Consider that Su-37 have quite high price buy cost and it's slighty worse, but it is much cheaper than -JL- to upgrade.
Vanilla upgrade cost:
1 to 2: 36k
2 to 3: 55k
3 to 4: 112k
4 to 5: 154k
5 to 6 (without NSU): 487k
9 to 10: 940k
Total cost to level 10 (considering also the buy cost): 3m
-JL- upgrade cost:
1 to 2: 147k
2 to 3: 200k
3 to 4: 294k
4 to 5: 400k
5 to 6 (without NSU): 716k
9 to 10: 1.9m
Total cost to level 10: 5.4m
Difference in damage:
- Vanilla: One-shots MiG-29s at level 6, at level 10 one-shots up to S/MTDs, need S damage or level 11 to one-shot MiG-31s, to one-shot F-22s/T-50s need level 13 with L damage;
- -JL-: One-shots MiG-29s at level 5, at level 10 one-shots up to MiG-31s, to one-shot F-22s/T-50s need level 11 with L damage.
Difference in damage special weapons:
HVAA:
- Vanilla: level 5 OR level 4 + S damage OR level 2 + M damage OR level 1 + L damage to one-shot MiG-29s, level 5 + L damage one-shots MiG-31s;
- -JL-: level 5 OR level 3 + S damage OR level 1 + M damage to one-shot MiG-29s, level 5 + M damage one-shots MiG-31s.
4AAM:
- Vanilla: level 3 + M damage OR level 1 + L damage to one-shot MiG-29s, level 5 + L damage one-shots up to Typhoons;
- -JL-: level 5 + S damage OR level 1 + M damage to one-shot MiG-29s, level 5 + L damage one-shots to S/MTDs.
QAAM:
- Vanilla: level 1 one-shots up to S/MTDs, level 5 one-shots up to YF-23s, level 4 + S damage to one-shot F-22s/T-50s, level 5 + L damage to one-shot F-35B WILDFIRE (emergency mission, phase 2 of co-op sorties);
- -JL-: level 1 one-shots up to MiG-31s, level 5 one-shots up to MiG-29 LOUDMOUTH, level 2 + S damage to one-shot F-22s/T-50s, level 4 + L damage to one-shot F-35B WILDFIRE.
Average cost to upgrade special weapons:
1 to 2: 55k
2 to 3: 115k
3 to 4: 360k
4 to 5: 780k
Total: 1.3m (4AAM costs more, HVAA and QAAM less)
Final note: usually put damage parts for standard missile or special weapons just to one-shot red targets is not suggested unless needed. HVAA and 4AAM for example, when they can one-shot MiG-29s is enough.