JP Morgan recently prepared an extensive report analyzing the top Nigerian banks.You can read the report here.JPM Nigerian Banks Research Report (658)
The major points are:

1. Nigerian banks appear expensive on a relative and absolute basis
2. Nigerian banks’ earnings growth is likely to outstip most other emerging markets over the next few years
3. Nigeria is one of the riskier emerging markets
4. The P/E ratio is expected to converge to other emerging markets
5. Oceanic bank is rated as a lower quality/high risk operation compared to its peers
6. GTB is the top pick as it is the only bank of the top 7 offering positive share price performance on a 12 month view while First Bank and Intercontinental are the least preferred of the top banks
7. Zenith and GTB have the higest quality operations while Union Bank has the lowest quality operation
8. Concerned that the risk management capability at Oceanic and Intercontinental Banks have not kept pace with their robust growth
9. Expect an average negative return of 21% for the top 7 Nigerian banks

Strengths
- Continued strong economic growth and sustained high oil prices
- Improving regulatory environment
- Presently well capitalised
- Increasing breadth of operations lowers risk to earnings because of diversification benefits
- Senior management teams at all teh banks are experienced bankers

- Weaknesses
- Lack of nationala identification system and lack of clearly functioning credit bureau
- Significant and widening gap between Nigerian banks and their international pairs in terms of valuation
- Untest risk controls
- Banks are a major portion of the NSE
- Lack of cross-border consolidated supervision

Opportunities
- Low penetration rates as evidenced by low deposit to GDP and loan to GDP ratios
- PPP projects to fund infrastructure spend
- Growth in retail segment
- More efficient capital structures
- Continued penetration of low cost retail deposits
- Improved efficiency

Threats
- Increasing competition has squeezed net interest margins
- Consolidation
- Growing NPLs
- Dependence on local investors
- Many of the banks depend on a few senior executives